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Odostomiinae

Odostomiinae, Odostomia snails and their allies, is a taxonomic subfamily of minute parasitic sea snails. These are marine heterobranch gastropod mollusks, or micromollusks, in the family Pyramidellidae.

Systematics

The subfamily Odostomiinae includes the tribe Liostomini Schander, Halanych, Dahlgren & Sundberg, 2003 , al name given to those genera which have an intorted protoconch. The rest of the genera however do not form a single monophyletic taxon.

This is one of eleven recognised subfamilies of the very voluminous gastropod family Pyramidellidae (according to the taxonomy of Ponder & Lindberg 1997): Odostomiinae, Turbonillinae, Chrysallidinae, Cingulininae, Cyclostremellinae, Sayellinae, Syrnolinae, Eulimellinae, Pyramidellinae, Odostomellinae and Tiberiinae.

However, in the taxonomy of Bouchet & Rocroi (2005), this subfamily also comprises the subfamilies Chrysallidinae, Cyclostremellinae and Odostomellinae, that they have downgraded to the rank of tribe.

  • Subfamily Odostomiinae Pelseneer, 1928
    • Tribe Odostomiini Pelseneer, 1928
    • Tribe Chrysallidini Saurin, 1958 (formerly subfamily Chrysallidinae)
    • Tribe Cyclostremellini D.R. Moore, 1966 (formerly subfamily Cyclostremellinae)
    • Tribe Odostomellini Saurin, 1959 (formerly subfamily Odostomellinae)

According to Schander, Van Aartsen and Corgan (1999) there are 33 genera in Odostominae with four possible additional genera of uncertain status.

Genera in the subfamily Odostomiinae (also classified as tribe Odostomiini)

Additional genera, potentially in the subfamily Odostomiinae

Distribution

This family is found worldwide, From the tropics to the poles.

Shell description

The shell of these snails has a blunt, heterostrophic protoconch, which is often pointed sideways or wrapped up. Most species in the subfamily have shells which are smaller than 13 mm. The texture of these shells is most often smooth but sometimes sculptured in various forms such as ribs and spirals. Their color is mostly white, cream or yellowish, sometimes with red or brown lines. The teleoconch is dextral coiled, but the larval shells are sinistral. This results in a sinistrally coiled protoconch. The columella has usually one, but sometimes several, spiral folds. The aperture is closed by an operculum.

Life habits

The Odostomiinae are ectoparasites, feeding mainly on other molluscs and on annelid worms, but some are known to feed on peanut worms and crustaceans (e.g. Sneli, 1972).

They do not have a radula. Instead their long proboscis is used to pierce the skin of its prey and suck up its fluids and soft tissues. The eyes on the grooved tentacles are situated toward the base of the tentacles. Between the head and the foot, a lobed process called the mentum (= thin projection) is visible. These molluscs are hermaphrodites.

References

  • Bouchet, P. & Rocroi, J.-P. (2005). "Classification and Nomenclator of Gastropod Families". Malacologia 53 (1-2): 1–397.
  • Pelseneer, P. (1928). "Les Parasites des Mollusques et les Mollusques parasites". Bulletin de la Sociéte Zoologique de France/Évolution et Zoologie 53 158–189.
  • Ponder, W.F. & Lindberg, D. R. (1997). "Towards a phylogeny of gastropod molluscs: an analysis using morphological characters". Zoological Journal of the Linnean Society 119 88–265.
  • Schander, C., van Aartsen, J. J., Corgan, J. C. (1999). "Families and genera of the Pyramidelloidea (Mollusca: Gastropoda)". Bollettino Malacologico 34 (9-12): 145–166.
  • Schander, C., Halanych, K. M., Dahlgren, T., Sundberg, P. (2003). "Test of the monophyly of Odostomiinae and Turbonillinae (Gastropoda, Heterobranchia, Pyramidellidae) based on 16S mtDNA sequences". Zoologica Scripta 32 (3): 243–254.
  • Sneli, J.-A. (1972). "Odostomia turrita found on Hommarus gammarus". Nautilus 86 (1): 23–24.

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